This invention concerns a vertical axis windmill having automatic swinging blades.
Principal requirements in the design of a windmill are:
1. Low cost of the windmill system. PA0 2. High Efficiency of wind energy conversion. PA0 3. Control of rotational speed of the windmill with varying wind velocity, PA0 4. Provision of safety means to ensure that the windmill will automatically release its wind load during periods of extremely strong wind and return to operation following such periods.
and
The conventional horizontal axis windmill is of rather high cost on account of its complex construction but otherwise generally meets these design requirements.
The vertical axis windmill is of relatively low cost on account of its simple construction and thus of considerable interest.
Among recent new designs for vertical axis windmills may be mentioned the improved Darrieus design by Raj Rangi and Peter South of the National Research Council of Canada, the variable geometry vertical axis windmill by P. J. Musgrove of Reading University, England and those designed by The University of Illinois and the McDonald and Douglas Co. Most of these designs are not self-starting and lack some of the design requirements enumerated above.